Summary of findings for the main comparison. Dietary fibre (all study interventions) versus control for the prevention of colorectal adenomas and carcinomas.
| Dietary fibre (all study interventions) versus control for the prevention of colorectal adenomas and carcinomas | ||||||
| Patient or population: people with a history of colorectal adenomas Settings: out‐patient setting Intervention: dietary fibre (all study interventions) versus control | ||||||
| Outcomes | Illustrative comparative risks* (95% CI) | Relative effect (95% CI) | No of participants (studies) | Quality of the evidence (GRADE) | Comments | |
| Assumed risk | Corresponding risk | |||||
| Control | Dietary fibre (all study interventions) versus control | |||||
| Number of participantswith at least one recurrent adenoma Follow‐up: 2 to 4 years | Study population | RR 1.04 (0.95 to 1.13) | 3641 (5 studies) | ⊕⊕⊝⊝ lowa,b | ||
| 349 per 1000 | 363 per 1000 (332 to 395) | |||||
| Moderate | ||||||
| 295 per 1000 | 307 per 1000 (280 to 333) | |||||
| Number of participantswith more than one adenoma Follow‐up: 3 to 4 years | Study population | RR 1.06 (0.94 to 1.20) | 2542 (2 studies) | ⊕⊕⊝⊝ lowa,b | ||
| 250 per 1000 | 265 per 1000 (235 to 300) | |||||
| Moderate | ||||||
| 340 per 1000 | 360 per 1000 (320 to 408) | |||||
|
Number of participantswith at least one adenoma 1 cm or greater Follow up: 3 to 4 years |
Study population | RR 0.99 (0.82 to 1.20) | 3224 (4 studies) | ⊕⊕⊝⊝ lowa,b | ||
| 102 per 1000 | 101 per 1000 (84 to 122) | |||||
| Moderate | ||||||
| 60 per 1000 | 59 per 1000 (49 to 72) | |||||
| Number of participantsdiagnosed with colorectal cancer Follow‐up: 3 to 4 years | Study population | RR 2.70 (1.07 to 6.85) | 2794 (2 studies) | ⊕⊕⊝⊝ lowa,c | The incidence of colorectal cancer is very low, so when risk was calculated by risk difference (RD), the difference between groups was very small. RD = 0.01, 95% CI 0.00 to 0.01 | |
| 4 per 1000 | 12 per 1000 (4 to 14) | |||||
| Moderate | ||||||
| 5 per 1000 | 14 per 1000 (5 to 16) | |||||
| *The basis for the assumed risk (e.g. the median control group risk across studies) is provided in footnotes. The corresponding risk (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI). CI: Confidence interval; RD: Risk difference; RR: Risk ratio | ||||||
| GRADE Working Group grades of evidence High quality: Further research is very unlikely to change our confidence in the estimate of effect. Moderate quality: Further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate. Low quality: Further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate. Very low quality: We are very uncertain about the estimate. | ||||||
a Risk of bias: downgraded by one level due to high risk of detection/performance bias and attrition bias. b Indirectness: downgraded by one level as adenoma was a surrogate outcome for CRC. c Imprecision: downgraded by one level as the data was under powered and the sample size was below the optimal information size.